Methods and systems for distributed thermoelectric heating and cooling

ABSTRACT

A thermoelectric device comprising an elongated panel, formed of a thermally insulating material, and having a plurality of thermoelectric elements comprising compacted conductors inside the insulating material and expanded conductors outside the insulating material is combined with other layers for leakage current interception, bodily fluid absorption, and pillars that preserve pressure re-distribution. The thermoelectric device may be integrated into a variety of surfaces or enclosures needing heating or cooling and manufactured using pre-existing automated equipment.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Application Ser. Nos. 61/680,405, files Aug. 7, 2012, and No. 61/716,671, filed Oct. 22, 2012, the contents of which are incorporated hereby reference.

BACKGROUND OF THE INVENTION

In our earlier U.S. patent applications Ser. Nos. 13/101,015 filed May 4, 2011 and Ser. No. 13/394,288 filed Mar. 5,2012 and PCT Application Serial Nos. PCT/US1 1/51227 filed Sep. 12, 2011 and PCT/US12/45443 filed Jul. 3, 2012, we describe a thermoelectric heating and cooling system comprising a connected string of thermoelectric elements woven or stuffed or layered into an insulating panel, which may be comprised of a soft material like foam, memory foam, bailing, or natural fabrics. A conductor material is expanded on either side of the panel to distribute heat on one side and cooling on the other. Such a material or surface upgraded with thermoelectric heating and cooling in this manner is called a distributed thermoelectric panel. In our earlier applications, integration of that insulating panel within mattresses, chairs, and blankets was also described. The end result was a relatively low cost, uniformly distributed addition of heating and cooling to bedding, seats, blankets, and other products.

SUMMARY OF THE INVENTION

The present invention provides various enhancements and improvements to heated and cooled products over the prior art, and also integration of thermoelectric heating and cooling panels into seat cushions, wheelchairs, hospital beds and bed tops, and pet beds. In addition, the present invention provides enhancements and improvements to the manufacturing of components of distributed thermoelectric panels for use in a variety of these and other products. Finally, the present invention provides improvements in the power delivery of distributed thermoelectric systems for increased mobility.

More particularly, in accordance with the present invention, we provide a distributed thermoelectric heating and cooling panel for use in hospital beds and wheelchairs that achieves low leakage current, compatibility with incontinence pads, and preservation of pressure distribution of underlying support surfaces. We provide a process for automated manufacturing of the components needed for distributed thermoelectric products utilizing both expandable stranded wires and flexible circuit configurations. We provide a heated and cooled seat topper that maintains the original and arbitrary shape of a seat cushion. Finally, we provide an elevated pet bed with heating and cooling for use by animals.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will be seen from the following detailed description, taken in conjunction with the accompanying drawings, wherein like numerals depict like parts, and wherein

FIG. 1 schematically illustrates a hospital bed with low leakage current;

FIG. 2 schematically illustrates a hospital bed compatible with an incontinence pad;

FIG. 3 schematically illustrates a hospital bed that maintains pressure redistribution;

FIG. 4 illustrates a housing for a control electronics and fan for the thermoelectric panel of the hospital bed in FIGS. 1-3;

FIG. 5 schematically illustrates an automated process for manufacturing the thermoelectric string and panel wherein the string utilizes stranded wire;

FIG. 6 schematically illustrates an automated process for manufacturing the thermoelectric string wherein the string utilizes flexible circuit material;

FIG. 7 schematically illustrates how power may be delivered wirelessly to a thermoelectric panel for increased mobility;

FIG. 8 schematically illustrates how power may be delivered by movable contacts to a thermoelectric panel for increased mobility;

FIGS. 9A and 9B schematically illustrate how the thermoelectric panel may be integrated into a seat cushion or bed top;

FIG. 10 schematically illustrates how the thermoelectric panel may be integrated into an elevated pet bed for animal use.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a hospital bed that is comprised of a distributed thermoelectric string containing expanded link wires 101, thermoelectric elements 103, and expanded loop wires 102. An electrical current flowing through the thermoelectric elements 103 causes heat to be moved to or from the bed surface depending on the direction of the current. The insulating foam 105, in addition to the sting, comprises the thermoelectric panel, which is also the top layer of the bed surface. A spacer mesh layer 106 underneath provides porous channel for a fan 112 to move air from the inlet 109 to the outlet 110, such air flows over the loops 102 to remove or insert heat from or to, respectively, the environment. The thermoelectric panel and air-flow layer are situated on top of a standard hospital mattress 114 supported by a frame 115. A box 111 housing the electronics, controls, power supply and fan 112 connects to the spacer mesh through a slot 116. Temperature sensors or over-temperature switches 113 or other devices turn-off or facilitate turning off the power when unsafe conditions are reached may be located at various positions. These sensors may also be used to control the bed surface to a constant temperature for thermostatic control. Without limitation, the distribution of the thermoelectric elements 103 may have varying density, or be placed in zones with separate or common temperature controls to optimize the system for the patient. Because the requirement for very low leakage current that could be experienced by patients in a hospital under fault conditions, an electrically conducting sheet 108 is situated between the patient and the thermoelectric string. This conducting sheet will preferentially divert any electrical current and minimize the remaining current that can flow through the patient should the waterproof cover 107 be compromised. The conducting sheet is preferably a metallized fabric that stretches in all four lateral directions in order to conform to the contour of the patient's body while lying on the bed. This conducting sheet with these properties is available from Less EMF Inc. and other suppliers. Without limitation, other conductive sheets could also serve this purpose such as screen, metal mesh, metallized mesh, and other materials containing metal or carbon.

FIG. 2 shows how the hospital bed of FIG. 1 is made compatible with an incontinence pad 201. In order to achieve the desired cooling of the skin to prevent pressure ulcers and perspiration, the layers separating the patient's body from the thermoelectric links 101 should be as thin as possible. Standard incontinence pads used in hospitals have thick absorption materials for bodily fluids. The incontinence pad 201 in FIG. 2 has thick areas 202 placed between the thermoelectric links. These thick areas act as fluid reservoirs and allow the portions of the incontinence pad 201 on top of the links 101 to be much thinner. Without limitation, these thick reservoir areas could be in an array or in parallel troughs located throughout the appropriate portion of the bed.

Many hospital beds have pressure redistribution characteristics to prevent or reduce the incidence of pressure ulcers. Some of these beds alternate pressure between two or more sets of supporting areas to prevent any one portion of the body from being subjected to high pressure for too long. Other beds have an array of mushroom shapes of foam in order to distribute pressure as much as possible. Still other beds have an array of air bladders in which air may flow from one bladder to the others to balance the pressure distribution. Cooling of the skin has been shown to further prevent or decrease the incidence of pressure ulcers, beyond the benefits of pressure-redistribution alone. Hence, a need exists to provide a cooling layer that retains the pressure distribution characteristics of the underlying surface.

FIG. 3 shows how the thermoelectric panel 105 is mounted on a matrix of spaced-apart support islands 301. These islands are able to displace vertically independent of each other. Even if the island 301 material is hard, their small size and independent movement allows for the pressure distribution to be retained. The spaces between the islands 302 permit airflow from the inlet 109 to the outlet 110. These islands may be comprised of spacer mesh, closed-cell foam, open cell foam, rubber, plastic, air balloons, fluid bladders, gels, or any other appropriate material. In the case of bladders, the fluid may be gel, oil, grease, wax, water, air, or other suitable liquid or gas. The thermoelectric panel 105 with the air flow layer comprising pillars 301 is placed on top of an existing pressure redistribution surface 302. Without limitation, the pressure redistribution surface 302 could be comprised of contoured foam, honeycomb gel, alternating pressure mechanisms, air bladder array, viscous fluid bag, or any other surface. These surfaces are available from Roho, Hill-Rom, Stryker, Sunrise, Pride Mobility and many others and apply to seating bedding including wheelchairs, hospital beds, and operating tables.

FIG. 4 shows a how the electromechanical components required for the operation of the thermoelectric panel may be housed in a single box 111. This box 111 has room for the power supply 403, the fan 112, and control electronics 402. The control electronics 402 provides for the functions of turning on and off 404, selecting the temperature or cooling power level 405, indicating the cooling intensity or temperature 406 with lights, and indicating fault conditions 407 such as over temperature or component failure. The box has a slot 116 for the spacer mesh or, without limitation, other channel for airflow and hooks 401 for hanging the box.

With the cooling power provided by each thermoelectric chip available today, typically hundreds of such chips are needed in a heated and cooled product. The thermoelectric string also needs to consist of hundreds of segments of expandable conductors such as stranded wire and hundreds of strain reliefs. Inserting each thermoelectric junction individually requires hundreds of insertions into the insulating and airflow layers. Hence, the need exists to automate the process for fabricating the thermoelectric string and for inserting the string into the insulator to make a thermoelectric panel.

FIG. 5 shows how the fabrication of the thermoelectric panel is achieved with three common automated machines that are readily available today. The first machine 501 cuts lengths of stranded wire and crimps a ferrule onto each end. The output of this machine is stranded wire segments with well-defined ends. Machines of this type are available from Schluniger and others.

The second machine 502 in FIG. 5 is one that makes circuit boards. This machine 502 has the ability to dispense glue, dispense solder, robotically place chips and other electronics components, and then flow the solder in an oven with a controlled temperature profile. To make a thermoelectric string, these functions are performed to generate strips 504 of thermoelectric junctions 103. The stranded wire links 101 are placed from strip 504 to another strip 504 and stranded wire loops 102 are placed on the outsides of the strips 504. Without limitation, groups of the links 101 and groups of the loops 102 may be placed manually or robotically in a carrier with comb-like slots to facilitate alignment of the ends of the links to the solder pads on the strips 504. The combination of links 101, loops 102, and strip 504 are moved through the reflow oven to melt and then harden the solder. After singulating the strips 504 into connected but individual thermoelectric junctions 103, a thermoelectric string is produced.

The third machine in FIG. 5 contains an array of sharp tubes 503 that is capable of puncturing many holes in the insulating layer simultaneously. This machine also has an array of holes 504 on top and bottom to guide the tubes and hold the insulating material in place, and a pneumatic or other system to generate the forces needed for complete puncture and insertion. Once the array of tubes has completely penetrated the insulating material, the loop 102 ends of the thermoelectric string are placed in the tubes either manually or robotically. Then, the array of tubes is removed in the opposite direction as it was inserted. A full thermoelectric panel is produced with all insertions accomplished simultaneously.

FIG. 6 shows another method for automating the production of the thermoelectric ribbon. In this case, a flexible circuit material 601 is used to replace both the stranded wires and the rigid strips of FIG. 5. One objective of the method shown in FIG. 6 is to not require etching of copper or patterning of the substrate. FIG. 6 Step 1 is a sheet of flexible circuit material 601 such as copper plated on a polyimide substrate. Without limitation, the flexible layer could be polyester, Mylar, or other suitable material. FIG. 6 Step 2 illustrates the flex material 601 after holes 602, 603, and 604 have been punched in a press or other suitable machine. Holes 602 on each corner are for registration and mounting of the board in a fixture, facilitating placement and alignment. Holes 603 remove the electrical connection between the ends of the chips that are placed in a later step. Holes 604 are for mounting and gripping of a strain relief that prevents large force disturbances from damaging the chips. FIG. 6 Step 3 shows a strain relief 605 made from epoxy or other hard or hardening material placed on the back of the flex circuit material. This strain relief 605 may be further foil led into or inserted into the gripping holes 604 for additional strain-relieving strength. FIG. 6. Step 4 shows the placement of solder paste 605 on copper pads in preparation for placement of the thermoelectric chips in a later step. FIG. 6 Step 5 shows the placement of n-type thermoelectric chips 607 and p-type thermoelectric chips 608 in an alternating fashion on the flex circuit material and adjacent to the solder paste placements 606. The assembly of FIG. 6 Step 5 is then processed in a solder reflow oven in which the solder paste forms a hard eutectic bond with the ends of the chips and with the copper pads. Without limitation, the epoxy or other glue placed in Step 3 may be cured after Step 5 in the same reflow oven. FIG. 6 Step 6 shows a final cut 609 into strips that represents a two dimensional thermoelectric ribbon that is ready for insertion into 105 as indicated in FIG. 6 Step 7. The insertion process achieves a back-to-back placement of the n- and p-type thermoelectric chips 607 and 608. The thermoelectric panel of FIG. 6 Step 7 now resembles the distributed thermoelectric panel that can be used for a seat cushion, bed surface, refrigerator wall, beverage wrapper, or other product needing heating or cooling and/or the ability to switch from one to the other.

Distributed thermoelectric panels using this invention and others by the same inventors enable the addition of heating and cooling to any seating or sleeping surface. However, many such surfaces require mobility, such as office chairs on wheels. These products require delivery of power to the panel using wireless or other means that does not inhibit or restrict the mobility. FIG. 7 shows one configuration wherein wireless power is delivered to the thermoelectric panel onside of chair 707. Wireless power devices available from PowerMat, Qualcomm, WiTricity and others deliver wireless power to mobile devices such as cellphones and automobiles. These wireless power transmitters 701 and 702 deliver power to a corresponding wireless receiver inside of a mobile device 703. The power level required for a thermoelectric panel is greater than 701 for cellphones, but less than 702 for charging batteries in an automobile. Hence, it is expected that either device could be scaled as needed to power an office chair 707, for example.

FIG. 8 shows another embodiment to permit mobility of products containing thermoelectric panels. In this case, conductive brushes 804 slide in contact with an underlying mat 801 containing alternating conducting electrodes 802 for a power supply voltage and 803 for ground. Without limitation, a plurality of brushes 804 are mounted on the ends of the spider 806 or on the wheels of any mobile device containing a distributed thermoelectric panel. As long as at least one of the brushes 804 is in contact with the power supply voltage electrodes 802 and at least one other brush is in contact with ground electrodes 803, power voltage yin 805 may be delivered to the thermoelectric panel in the chair using the diode array circuit in FIG. 8. All of the electrodes 802 and 803 are electrically connected to both ends of the diode array 802, and the rectification function of the diodes insures that power Vin 805 flows from the power supply source to ground.

One application for heated and cooled seating is a seat or back cushion that is sized comparably to such cushions readily available and powered using a cord or a battery. Such a cushion is illustrated in FIGS. 9A and 9B. The air inlet 109 is in the front for a seat bottom cushion or at the top for a seat back cushion. Without limitation, the air inlet could be partially or wholly the distributed porosity of the cover 107. The thermoelectric panel 105 is placed on top of a spacer mesh airflow layer 102. Blower fan 904 is located in the back of the seat bottom cushion or the lower end of a seat back cushion. The air is pulled from the inlet 109 by the blower fan and exhausted to air outlet 110. Depending on the arrangement of the seat cushion, the preferred direction of the exhaust 110 might be blocked, so alternative outlets 901 may be added which have different directions of airflow. A cover 107 separates the seat surface from the wires 101 of the thermoelectric panel. For purposes of comfort and performance, the cover 107 may comprise soft but thermally conductive material such as carbon fibers, glycerin, gel, or unexpanded polyurethane. The entire heating and cooling system may be contained within the size and shape of a conventional seat cushion.

FIG. 10 shows a heated and cooled bed for a pet or other animal for comfort indoors or outdoors. Many existing pet beds are elevated to provide ventilation from underneath. In FIG. 10, the elevated support layer 952 and frame 953 and 954 are retained. The thermoelectric wires 101 are brought through to the top of the support layer 952 or are in good contact from underneath. The air inlet 109 may be some of or all of the perimeter of the spacer-mesh 106 with fan 904 pulling the air from these inlets to the outlet 110. Cover 951 separates the pet from the wires 101 of the thermoelectric panel.

Various changes may be made without departure from the spirit and scope of the present invention. 

1-27. (canceled)
 28. A thermoelectric device for heating or cooling, comprising: a panel comprising a substrate material that is electrically insulating, wherein the panel comprises a plurality of thermoelectric elements comprising compacted conductors located at least in part inside the substrate material and expanded conductors located at least in part outside the substrate material as part of a flexible circuit, wherein the plurality of thermoelectric elements subjects a space adjacent to the panel to heating or cooling at low leakage current upon application of power to the plurality of thermoelectric elements; and a frame adjacent to the panel, wherein the frame supports the panel during operation of the thermoelectric device to subject the space adjacent to the panel to heating or cooling.
 29. The device of claim 28, further comprising a waterproof cover disposed between the expanded conductors and a surface of the thermoelectric device.
 30. The device of claim 28, further comprising a top pad with reservoirs disposed between the expanded conductors.
 31. The device of claim 28, further comprising an airflow layer adjacent to the panel.
 32. The device of claim 31, wherein the airflow layer comprises a porous cover combined with a blower fan, and wherein air from the blower fan is sourced from one or more sides or edges of the porous cover and exits in multiple directions.
 33. The device of claim 28, further comprising a wireless power transmitter and receiver for powering the thermoelectric device.
 34. The device of claim 28, wherein the substrate material is thermally insulating.
 35. The device of claim 28, further comprising a plurality of panels, wherein the plurality of panels is arranged to be selectively turned on and off to regulate cooling or heating in response to local pressure, local temperature, local body sensitivity, or combination thereof.
 36. A thermoelectric device for heating or cooling, comprising: a panel comprising a substrate material that is electrically insulating, wherein the panel comprises a plurality of thermoelectric elements comprising compacted conductors located at least in part inside the substrate material and expanded conductors located at least in part outside the substrate material as part of a flexible circuit; a matrix of support pillars adjacent to the panel, wherein the support pillars are independently moveable, and wherein the support pillars redistribute a pressure applied to a surface of the panel; and a frame adjacent to the panel, wherein the frame supports the panel during operation of the thermoelectric device to subject the space adjacent to the panel to heating or cooling.
 37. The device of claim 36, wherein the support pillars comprise a spacer mesh, foam, fluid bladder, gel, or any combination thereof.
 38. The device of claim 36, wherein the matrix of support pillars is included in an air flow layer.
 39. The device of claim 38, wherein the airflow layer comprises a porous cover combined with a blower fan, and wherein air from the blower fan is sourced from one or more sides or edges of the porous cover and exits in multiple directions.
 40. The device of claim 36, further comprising a plurality of panels, wherein the plurality of panels is arranged to be selectively turned on and off to regulate cooling or heating in response to local pressure, local temperature, local body sensitivity, or combination thereof.
 41. A thermoelectric device for heating or cooling, comprising: a panel comprising a substrate material that is electrically insulating, wherein the panel comprises a plurality of thermoelectric elements comprising compacted conductors located at least in part inside the substrate material and expanded conductors located at least in part outside the substrate material as part of a flexible circuit; a frame adjacent to the panel, wherein the frame supports the panel during operation of the thermoelectric device to subject the space adjacent to the panel to heating or cooling; and a movable conductor in contact with an array of stationary electrodes in electrical communication with a power source, wherein the movable conductor and array of stationary electrodes provide power to the plurality of thermoelectric elements upon contact between the movable conductor and the array of stationary electrodes.
 42. The device of claim 41, wherein a given electrode of the array of stationary electrodes is connected to the power source or ground voltage and adapted to come in contact with the movable conductor.
 43. The device of claim 42, further comprising diodes or rectifiers for selecting which electrode of the array of stationary electrodes provides power.
 44. The device of claim 41, wherein the movable conductor is mounted on or adjacent to wheels of a rolling chair or rolling bed.
 45. The device of claim 41, wherein the power source is a battery.
 46. The device of claim 41, further comprising a plurality of panels, wherein the plurality of panels is arranged to be selectively turned on and off to regulate cooling or heating in response to local pressure, local temperature, local body sensitivity, or combination thereof.
 47. The device of claim 41, wherein the movable conductor is included in a movable conducting brush. 